Boring tool

ABSTRACT

A boring tool comprises a rotating tool body, a tool slide transversely displaceable therein, a cutting plate arranged on the tool slide and a micrometer screw for adjusting the tool slide, this micrometer screw being mounted transversely to the axis of rotation of the boring tool so as to be rotatable and axially non-displaceable. The micrometer screw is mounted in the tool body at a distance from the tool slide and drives a drive slide displaceable transversely to the axis of rotation of the tool body. A transfer lever is pivotally mounted in the space between drive and tool slides and engages with one arm on the drive slide and with the other arm on the tool slide such that when the drive slide is displaced the tool slide is entrained in the opposite direction to the drive slide. The masses of drive slide, on the one hand, and tool slide, including cutting plate, on the other hand, are determined such that the entire arrangement of drive and tool slides is always balanced in relation to the axis of rotation during their movement in opposite directions.

The invention relates to a boring tool comprising a tool body which canbe clamped into a rotatingly driven spindle and rotates with thisspindle, a tool slide displaceable in a guide means in the tool bodytransversely to its axis of rotation, a cutting plate interchangeablyattached to the tool slide for removing material, a micrometer screw foradjusting the tool slide in its guide means, this micrometer screw beingmounted in the tool body transversely to its axis of rotation so as tobe rotatable and axially non-displaceable, and adjustablecounterbalancing masses for balancing the boring tool in relation to itsaxis of rotation.

A boring tool of this type is known from DE-A1-35 10 259. With thisboring tool, the unbalanced masses have to be adjusted separately fromthe adjustment of the tool slide in order to bring about the balancingof the boring tool.

The object of the invention is to develop a boring tool of the generictype further such that the displacements of mass occurring during theradial adjustment of the tool slide are automatically counterbalanced sothat no troublesome, out-of-balance forces result.

This object is accomplished in accordance with the invention in that

A) the micrometer screw (17) is mounted in the tool body (2) at

a distance above the tool slide (7), leaving a space (16) free anddrives a drive slide (19) displaceable in the tool body (2) transverselyto its axis of rotation (B);

B) a two-armed transfer lever (22) is pivotally mounted in the space(16) between drive and tool slides (19 and 7, respectively), this leverengaging with its one arm on the drive slide (19) and with its other armon the tool slide (7) such that when the drive slide (19) is displacedby the micrometer screw (17) the tool slide (7) is entrained in theopposite direction to the drive slide (19) in accordance with theleverage ratio of the transfer lever (22); and

C) the drive slide (19) forms at the same time the adjustablecounterbalancing mass, wherein this mass, on the one hand, and the massof the tool slide (7), including cutting plate (15), on the other hand,are determined such that the entire arrangement of drive and tool slides(7, 19) is always balanced in relation to the axis of rotation (B)during their movement in opposite directions.

With a known boring tool of a different type (DE-C2-39 26 026), a leverengaging on a sleeve via a ball is pivoted by axial displacement of thesleeve and this lever, with its other end, radially adjusts a head partwhich is flexible in itself and, for its part, supports a boring tool.During the radial adjustment of the head part, a radial adjustment of aslide takes place at the same time in the opposite direction via anadditional ball which automatically results in a compensation ofimbalances.

Due to the use of a separate slide for compensating imbalances which isnot connected directly to a lever but requires a separate part, namelythe ball 25, for its drive, this arrangement is complicated andsusceptible to failures and is not comparable to the inventive solutionbecause, in this case, the transfer lever directly triggers not only theadjustment of the tool slide but also the compensation of imbalances bydisplacing the drive slide. An additional part for compensatingimbalances corresponding to the ball of the known arrangement istherefore omitted in the invention.

The following description of a preferred embodiment of the inventionserves to explain the invention in greater detail in conjunction withthe attached drawings. In the drawings:

FIG. 1 is a schematic view of an axial section of a boring tool;

FIG. 2 is a partially cutaway side view of the boring tool in thedirection of arrow A in FIG. 1;

FIG. 3 is a part-sectional view similar to FIG. 1 with a tool slide in adifferent position and

FIG. 4 is a bottom view of a cover for the boring tool from FIGS. 1 to3.

The boring tool 1 illustrated in the drawings comprises an essentiallycircular-cylindrical tool body 2 which is outwardly enclosed by a sleeve3, preferably consisting of a chrome alloy. The tool body 2 has a shaft4 projecting in one piece which can be clamped, e.g. by means of achuck, into a rotatingly driven spindle 5 of a machine tool so that theboring tool 1 rotates about a common axis of rotation B together withthe spindle 5.

A radially displaceable tool slide 7 is inserted into a recess 6extending transversely to the axis of rotation B in the lower region ofthe tool body 2. A screw bolt 8 which penetrates a recess 9 of the toolslide 7 serves to clamp and fix the tool slide 7 in its set position.The complementary cross-sectional shapes of the recess 6 and the toolslide 7 are apparent from FIG. 2, according to which the essentiallycircular-cylindrical tool slide 7 is flattened on its underside. A flatcover 12 connected to the tool body 2 by screws 11 abuts on this flatunderside and thereby secures the tool slide 7 against rotation.

A cutting plate carrier 14 is held by means of a screw 13 on the oneside of the tool slide 7 (located to the right in FIGS. 1 and 3) and acutting plate 15 serving to remove material from a workpiece isinterchangeably secured in this carrier in a manner known per se.Corresponding boring or internal turning radii can be set by radiallyadjusting the tool slide 7 and, therefore, the cutting plate 15.

The tool slide 7 is radially adjusted with the aid of a micrometer screw17 which is arranged in the tool body 2 at a distance above the toolslide 7, leaving a space 16 free inbetween, and which is mounted in thetool body 2 transversely to the axis of rotation B of the boring tool soas to be rotatable but axially non-displaceable. The micrometer screw 17has on its one side (located to the left in FIG. 1) a head 18 with aregular scale and a vernier scale (FIG. 2), with which the micrometerscrew 17 can be finely adjusted. The shaft of the micrometer screw 17which is provided with an external thread engages in a threaded bore ofa drive slide 19 which is guided in the tool body 2 so as to benon-rotatable but axially displaceable so that when the micrometer screw17 is rotated the drive slide 19 performs a lifting or shifting movementwhich is directed radially transversely to the axis of rotation B and islimited on both sides.

A two-armed transfer lever 22 is mounted in the space 16 between thetool slide 7 and the drive slide 19 by means of an axle 21 supported onthe tool body 2. The transfer lever 22 engages with its one arm (upperarm in FIG. 1) in a groove 23 of the drive slide 19 and with its otherarm in a groove 24 of the tool slide 7. Since the axle 21 is arrangedbetween the tool slide and the drive slide 19 so as to extendtransversely to their directions of displacement, when the drive slide19 is displaced the tool slide 7 is taken along in accordance with theleverage ratio of the transfer lever 22, namely in the oppositedirection to the drive slide. In this way, the tool slide 7 is finelyadjusted by rotation of the micrometer screw 17.

The leverage ratio of the transfer lever 22 can as such be freelyselected. In the illustrated embodiment, the arm of this lever engagingon the drive slide 19 is longer than the arm engaging on the tool slide7 and so a reduction ratio exists between the displacement movements ofthe slides 7, 19 in such a way that a bigger displacement of the driveslide 19 triggers a smaller displacement of the tool slide 7 which isfavorable for a fine adjustment of the tool slide 7.

As illustrated, the arms of the transfer lever 22 each have at theirends a cylindrically ground head 25 and 26, respectively. Thecylindrical head 25 fits exactly into the groove 23 of the drive slide19. The groove 24 of the tool slide 7 is limited on one side by a freelyprojecting, web-like groove wall 27 which is engaged by a screw 28accessible from the outer side of the boring tool 1. By turning thescrew 28 inwards accordingly, the web 27 can be deformed such that itabuts fittingly on the cylindrical head 26 of the transfer lever 22 andso a clearance-free connection is ensured between the slides 7, 19, onthe one hand, and the transfer lever 22, on the other hand.

During the production of the tool slide 7, including cutting platecarrier 14 and cutting plate 15, as well as of the drive slide 19, theirmasses are determined and adapted to one another such that the entirearrangement of drive and tool slides, including transfer lever 22, isalways balanced in relation to the axis of rotation B during themovement in opposite directions of the two slides 7 and 19. Due to themovement in opposite directions of the two slides 7 and 19, the massesdisplaced radially in opposite directions counterbalance one another sothat no imbalance can occur at the boring tool 1 in any position of thecutting plate 15.

As is apparent from FIG. 1, the cover 12 closing the boring tool 1 atthe bottom contains a threaded bore 29 which extends essentiallyparallel to the direction of movement of the slides 7 and 19. A screw 31is radially adjustable in this bore. The screw 31 serves as anadditional, adjustable balancing weight and can, for example, be used tocompensate for any imbalance of the masses of different cutting plates15 and/or cutting plate carriers 14.

FIG. 1 shows the tool slide 7 essentially in its one (left) extremeposition while this slide is illustrated in FIG. 3 in its other (right)extreme position. In these two extreme positions of the tool slide 7,the drive slide 19 connected thereto by the transfer lever 22 is locatedeach time in a diagonally opposed position.

We claim:
 1. Boring tool comprising a tool body adapted to be clampedinto a rotatingly driven spindle and rotating with said spindle, a toolslide displaceable in a guide means in the tool body transversely to itsaxis of rotation, a cutting plate interchangeably attached to the toolslide for removing material, a micrometer screw for adjusting the toolslide in its guide means, said micrometer screw being mounted in thetool body transversely to its axis of rotation so as to be rotatable andaxially non-displaceable, and adjustable counterbalancing masses forbalancing the boring tool in relation to its axis of rotation,characterized in thatA) the micrometer screw (17) is mounted in the toolbody (2) at a distance above the tool slide (7), leaving a space (16)free and drives a drive slide (19) displaceable in the tool body (2)transversely to its axis of rotation (B); B) a two-armed transfer lever(22) is pivotally mounted in the space (16) between said drive and toolslides (19 and 7, respectively), said lever engaging with one arm on thedrive slide (19) and with its other arm on the tool slide (7) such thatwhen the drive slide (19) is displaced by the micrometer screw (17) thetool slide (7) is entrained in the opposite direction to the drive slide(19) in accordance with the leverage ratio of the transfer lever (22);and C) the drive slide (19) forms at the same time the adjustablecounterbalancing mass, wherein this mass, on the one hand, and the massof the tool slide (7), including cutting plate (15), on the other hand,are determined such that the entire arrangement of drive and tool slides(7, 19) is always balanced in relation to the axis of rotation (B)during their movement in opposite directions.
 2. Boring tool as definedin claim 1, characterized in that the drive slide (19) and the toolslide (7) each have a groove (23 and 24, respectively), one arm of thetransfer lever (22) engaging in each of said grooves with a cylindricalhead (25 and 26, respectively).
 3. Boring tool as defined in claim 2,characterized in that the groove (24) in at least one of the slides (7,19) has a web-like groove wall (27) adapted to be pressed by a screw(28) towards the head (26) of the transfer lever (22).
 4. Boring tool asdefined in claim 1, characterized in that the transfer lever (22)reduces the displacement movement of the tool slide (7) relative to thedrive slide (19).
 5. Boring tool as defined in claim 1, characterized inthat a cover (12) is connectable to the tool body (2), said covercontaining an additional, adjustable balancing weight (31) forcounterbalancing the weights of different cutting plates (15).
 6. Boringtool as defined in claim 5, characterized in that the cover (12) isattached to the tool body (2) beneath the tool slide (7) and securesthis slide against rotation.